Chester e



UNITED STATES PATENT OFFICE.

CHESTER E. ANDREWS, OF PITTSBURGH, PENNSYLVANIA, ASSIGNOR TO THE SELDEN COMPANY, OF PITTSBURGH, PENNSYLVANIA, A' CORPORATION OF DELAWARE.

I l-METHYL-Z-AMINO-l ISOPROPYL-S-NITROBENZENE.

No Drawing.-

To all whom it may concern:

Be it known that I, Cnris'rnn E. ANonnws, a citizen of the United States, residing at Pittsburgh, in the county of Allegheny and State of Pennsylvania, have invented certain new and useful Improvements in 1 Methyl 2 Amino 4 Isopropyl 5 Nitrobenzene, of which the following is a specification.

The present invention relates to the production of amino compounds of cymene and intermediate products.

The preparation of 1-methyl-2-amino-4- isopropyl benzene, or amino cymene has already been described in my copending application 191,245 filed September 13, 1917, the process consisting briefly in nitrating cymene by dissolving the cylnene in sulfuric acid and adding thereto a nitrating mixture comprising sulfuric and nitric acids, while agitating the mixture, and subsequently re ducing the nitro body thereby produced, for example by iron and hydrochloric acid. This material, amino cymene, which may be in either the crude or' purified state, forms the starting material of the present process.

To introduce a nitro group into a position para to the amino group, it is first necessary to block off the amino group to prevent action of the nitrating' material thereupon. This operation may. conveniently be effected by adding about one and one-half to two molecular equivalents of glacial acetic acid, and heatin the mixture to boiling for about 15 to 20 ours in a vessel rovided with a reflux condenser. During this operation theNH, group of the amino compound is transformed into the NHCOCH, group, which is resistant to the nitrating mixture. The reaction mixture isthen cooled .where upon the same solidifies, and the mono acetyl amino cymene'is then nitrated. This operation is most conveniently carried out as follows: 19 parts of the acetyl amino cymene are dissolved in 84 parts of sulfuric acid of about 98% strength and the mixture cooled to 0 C. or thereabout. A nitrating solution containing about 13 parts of sulfuric acid of 98% strength and 10 parts of nitric acid of strength is then added slowly to the sulfuric acid solution of the acetyl-amino body while the mixture is vigorously stirred and while the temperature is maintained at about 0 C. It is essential that the temperature be kept down during this operation.

Specification of Letters Patent.

Patented Sept. 2, 1919.

Application filed September 22, 1917. Serial No. 192,783.

By the time all of the nitratino acid has been added, the nitration is substantially complete and the product consists essentially of '1-methyl-2-acctyl-amino-4-isopropyl-5-nitro benzene. The reaction mixture is poured into a large quantity of ice water, that is to say water containing cracked ice which is constantly stirred, and a yellowish precipitate is produced consisting of para nitro acetyl-amino cymene.

This material may be then treated directly for the reduction of the nitro group to an amino group, or may be treated for the removal of the acetyl roup. The former of these two methods is or most purposes preferable, and may be conducted by adding hydrochloric acid and iron and heatin the mixture, producing I-methyI-Q-acety l amin0-4-isopropyl-5-amino benzene, which material may be separated from the reaction mixture by crystallization or by extraction with a suitable solvent such as fusel oil or ether.

The acetyl group may then be removed by boiling the entire quantity of the compound produced as above dcscribed,with 50 parts of concentrated hydrochloric acid until all is dissolved, and upon cooling the hydrochlorid of 1-methyl-2-amino-4-isopropyl-5-amino benzene separates out in the form of crystals. This mode of operation is in many ways preferable, since there is produced as an -intermediate product l-methyl-Q-acetyl amino- 4-isopropyl-5-amino benzene, which material has the advantage of containing two amino roups, only one of which is diazotizable;

then caused to react with a suita le com- "g F v 131mg The second mode of treating 1-me'thyl-2- coupling with an aromatic h droxfeqm acetyl amino-4-isopropyl-5-nitro benzene is pound, or enaromatio amino compound-"for by removing the acetyl group, which may be the production of dyestufi's by the method 5 effected by boiling the entire quantity pro-' above referred to. p

5 duced asaboie described, with 50 parts of The compounds 1-methyl-2-amino-4-isoconcentrated hydrochloric acid, until the propyl-5-amino benzene and l-methyl-Q- same completely dissolves, when upon coolamino-4-isopropyl-5-nitro benzene are both ing crystals of hydrochlorid of 1-methyl-21. suitable for the production of dyestuffs by amino-44sopropyl-5-nitro benzene are prothe method above referred to.-

10 duced. These crystals may be purified by The reactions taking place in the process:

recrystallization from hydrochloric acid soof the present inventio may-beillustrated lotion, and the product then is suitable for conveniently asfollows:

H: 0H3 om First method:

on. om GHQ /\NHCOCH3 -NnoocH3 NH, t Reduced by -Fe+HCl-+ V 1 Boiled with HCl F No,-

NH-gcH- i m e 0 mm)?" Second method: V Whatl claim is:'

A body. having the formula 2113 7 0H3 v v e m 40' HCOCHz NHz-HC1 v Boil with HCl-) I R OQN OgN o N \l/ i B I 45 011mm omens i a Y a w, in which R is hydrogen or a radifilis'table in the presence of HNO at 0 C.

In testimony whereof I affix my signature.

CHESTER E. ANDREWS. 

